This invention relates to a color signal separating apparatus and especially to a color signal separating apparatus for separating and digitizing signals corresponding only to particular colors from image signals provided by a monitor camera thereby to obtain signals corresponding to the particular colors. More particularly, the invention relates to an apparatus suited for use with a fruit harvesting machine as means to exclude the sky, leaves and the like which lie in the background of fruit from image signals provided by a monitor camera acting as means to detect positions of fruit to be harvested.
In one known type of color signal separating apparatus, the monitor camera for picking up the image of an object includes an optical filter for passing particular colors only, in order to obtain signals corresponding to the particular colors from image signals from the monitor camera. Another type of known apparatus carries out logical processing to obtain a sum of or a difference between color signals corresponding to particular colors among a plurality of color signals output by a color video camera.
In order to digitize the color signals, the color signals are first stored in a frame memory or the like and are thereafter put to digital logical processing. Such a process requires a complicated construction and the logical processing is time-consuming. Where the optical filter is employed, it is necessary to have available many kinds of filter corresponding to particular colors to be determined.
Futhermore, both of the known apparatus noted above have the serious disadvantage that the image signals obtained under conditions where brightness or luminance levels deviate from a certain value cannot be differentiated without greatly complicating software therefor. Especially, it is impossible to maintain the brightness to a certain level where the apparatus is used with the above-noted fruit harvesting machine which operates outdoors. On the other hand, the particualr colors to be sampled have a certain range, further complicating the process with the known construction, and simple improvements in hardware are inadequate to permit the image signals to be processed on real time basis.